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Quantificação de Teores de Lítio em Rochas por LIBS: Avaliação do Efeito do Gating nas Correlações Espectrais
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Orientador(es)
Resumo(s)
O aumento da exploração mineira de minérios de lítio, impulsionado pela crescente produção
de baterias de iões de lítio, exige métodos analíticos portáteis, rápidos e eficazes para a
avaliação de teores em amostras geológicas. A espectroscopia de plasma induzido por laser
(LIBS,
Laser-Induced Breakdown Spectroscopy) tem vindo a afirmar-se como uma técnica
amplamente utilizada na prospeção mineira, devido à sua portabilidade, rapidez de análise e
reduzida preparação das amostras. Neste contexto, constitui uma alternativa a métodos
expeditos como a fluorescência de raios X portátil (pXRF), que não permite a quantificação
fiável de elementos leves.
Contudo, a quantificação de lítio por LIBS é condicionada por efeitos de matriz, fenómenos de
autoabsorção e variabilidade experimental. Assim, o presente trabalho avalia o potencial do
LIBS para a estimativa quantitativa preliminar de lítio, com particular enfoque na aplicação degating temporal como estratégia para melhorar a qualidade do sinal espectral. Foram
analisadas amostras minerais litiníferas recorrendo a um analisador portátil SciAps Z300,
comparando resultados obtidos com e sem
gating e utilizando diferentes linhas de emissão
do lítio.
Os resultados demonstram que a aplicação adequada de
gating temporal melhora a
estabilidade do sinal e a correlação entre as intensidades LIBS e os teores de lítio determinados
por métodos laboratoriais de referência, confirmando a viabilidade do LIBS como ferramenta
de triagem quantitativa preliminar em prospeção mineira.
The increasing exploitation of lithium-bearing mineral resources, driven by the growing production of lithium-ion batteries, requires rapid, portable and effective analytical methods for the assessment of lithium contents in geological samples. Laser-Induced Breakdown Spectroscopy (LIBS) has become an increasingly adopted technique in mineral exploration due to its portability, fast analysis and minimal sample preparation requirements. In this context, it represents an alternative to rapid screening methods such as portable X-ray fluorescence (pXRF), which does not allow reliable quantification of light elements. However, lithium quantification by LIBS is affected by matrix effects, self-absorption phenomena and experimental variability. Accordingly, this work evaluates the potential of LIBS for the preliminary quantitative estimation of lithium, with particular emphasis on the application of temporal gating as a strategy to improve spectral signal quality. Lithium-bearing mineral samples were analysed using a portable SciAps Z300 analyser, comparing results obtained with and without gating and using different lithium emission lines. The results demonstrate that the appropriate application of temporal gating improves signal stability and enhances the correlation between LIBS intensities and lithium contents determined by reference laboratory methods, confirming the viability of LIBS as a preliminary quantitative screening tool in mineral exploration.
The increasing exploitation of lithium-bearing mineral resources, driven by the growing production of lithium-ion batteries, requires rapid, portable and effective analytical methods for the assessment of lithium contents in geological samples. Laser-Induced Breakdown Spectroscopy (LIBS) has become an increasingly adopted technique in mineral exploration due to its portability, fast analysis and minimal sample preparation requirements. In this context, it represents an alternative to rapid screening methods such as portable X-ray fluorescence (pXRF), which does not allow reliable quantification of light elements. However, lithium quantification by LIBS is affected by matrix effects, self-absorption phenomena and experimental variability. Accordingly, this work evaluates the potential of LIBS for the preliminary quantitative estimation of lithium, with particular emphasis on the application of temporal gating as a strategy to improve spectral signal quality. Lithium-bearing mineral samples were analysed using a portable SciAps Z300 analyser, comparing results obtained with and without gating and using different lithium emission lines. The results demonstrate that the appropriate application of temporal gating improves signal stability and enhances the correlation between LIBS intensities and lithium contents determined by reference laboratory methods, confirming the viability of LIBS as a preliminary quantitative screening tool in mineral exploration.
Descrição
Palavras-chave
LIBS lítio prospeção mineira gating temporal análise portátil calibração espectral